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Nucleus — GCSE Biology Definition | GradeGen

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Biology
Key terms
Nucleus

GCSE Biology · key term

Nucleus

Definition

A structure in a eukaryotic cell that contains most of its genetic material.

Used by AQA, Edexcel and OCR

How each exam board covers it

AQA GCSE Biology · 8461

Specification 4.1.1.1, 4.1.1.2, 4.1.2.1 · Paper 1

A structure in a eukaryotic cell that encloses its genetic material.
A eukaryotic cell has a cell membrane surrounding its cytoplasm, and its genetic material is enclosed inside a nucleus. The nucleus is therefore a separate structure within the cell rather than simply an area of exposed DNA.
Revise: Eukaryotes and Prokaryotes
The sub-cellular structure that contains genetic material and controls the activities of a eukaryotic cell.
Revise: Animal and Plant Cell Structure

Exam tips

1
State precisely where the DNA is: eukaryotic DNA is enclosed in a nucleus, whereas prokaryotic DNA is not enclosed in a nucleus.
2
A plasmid is a small ring of bacterial DNA, not the bacterium's main DNA loop and not a nucleus.
3
Keep the levels of organisation in the correct order: nucleus → chromosomes → DNA → genes.

Related key terms

Cell membrane
Eukaryotic cell
Plasmid
Prokaryotic cell
Cell wall

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A sub-cellular structure that contains the chromosomes in plant and animal cells.

Revise: Chromosomes

AQA Biology past papers

Edexcel GCSE Biology · 1BI0

Specification 1.1 · Paper 1, Paper 2

A structure in a eukaryotic cell that contains genetic material and controls the cell's activities.
Animal and plant cells are eukaryotic. Their DNA is enclosed inside a nucleus, and they contain membrane-bound organelles such as mitochondria. Bacterial cells are prokaryotic: they have no nucleus, so their chromosomal DNA lies free in the cytoplasm.
Revise: Sub-Cellular Structures

Edexcel Biology past papers

OCR GCSE Biology A · J247

Specification B1.1b · Paper 1 (Foundation), Paper 3 (Higher)

Plant and animal cells are eukaryotic: they have a nucleus containing most of their genetic material. Bacteria are prokaryotic: they are cells too, but they do not have a nucleus.
Revise: Sub-cellular structures

OCR Biology A past papers

OCR GCSE Biology B · J257

Paper 1 (Foundation), Paper 2 (Foundation), Paper 3 (Higher), Paper 4 (Higher)

A membrane-bound structure in a eukaryotic cell that contains its genetic material.
Plant and animal cells are eukaryotic cells. Their genetic material is enclosed within a membrane-bound nucleus.
Revise: Cells and Microscopy

OCR Biology B past papers